Deontological Theory
Deontological theory is a normative theory, which asserts that one must follow “his or her obligations to another individual or society because upholding one's duty is what is considered ethically correct”[1] . Deontologists believe that morality is a matter of duty[2] , and we as individuals have a moral obligation to act in accordance with duty.
The word deontology stems from the Greek word “deon”, which translates to “one must", and in deontology a right choice depends on its conformity with a moral norm[3] . Those who subscribe to deontological theories of morality, stand in opposition to consequentialists.

In deontological ethics, certain kinds of actions are intrinsically right and others are intrinsically wrong[4] . To kill the innocent, torture, lie or cheat are always considered morally wrong actions under pure deontological theory, even if doing so would prevent a worse action from occurring[5] . Branches of Deontological Theory
There are many ethical theories under the deontological umbrella which follow the rule-based approach to determining morally right actions. These theories include motivationalism[6] , legalism[7] , duty theories, rights theories, contractarianism, and monistic deontology. "The Golden Rule" and divine command theory are also theories framed through a deontological lens. Agent-centered theory of deontology states that people’s moral choices are determined by personal obligation and permission. For example, a parent is obligated to treat his/her child as more important than other people. At the other end of the spectrum, there is no obligation for other parents to treat that child any differently than anyone else. Under the agent-centered theory of deontology, individuals have personal obligations that are universally understood, yet remain individualistic in nature. There are three versions of agents-centred deontology. One version which focuses on mental state, the other on actions, and the final version emphasizes the combination of intentions and action. All are used to determine the morally relevant agency of individuals[8] . Patient-centered theory emphasizes individual rights rather than personal duty. In the patient-centered theory of deontology, individuals have the autonomy not be used for moral good against their will. For example, you cannot kill a murderer without permission, even if it would amount to saving innocent lives. Famous Deontologists
German Philosopher Immanuel Kant (1724 – 1804) is considered the most famous deontologist of all time. His primary literature on ethics includes the Groundwork for the Metaphysics of Morals (1785), the Critique of Practical Reason (1788), and the Metaphysics of Morals (1797). Kant’s philosophy states that moral reasoning is based on standards of rationality, which he labeled the “categorical imperative ”. The categorical imperative is meant us to guide us to the right action, regardless of circumstances[9] . W.D. Ross (1877 – 1967) is a contemporary deontologist who believed that moral issues could not be reduced to one fundamental question. Ross proposed a pluralistic, mixed deontological theory of obligation, which recognizes several irreducible moral relationships, duties and principles”[10] . Ross developed seven prima facie duties that we need to take into account in determining if an action is the right one. “Among the things we need to take into account are promises we have made, the need to avoid harming other, gratitude to benefactors, and the amount of good our actions will produce”[11] . According to Ross, we must fulfill prima facie duties unless they conflict with another prima-facie duty of greater weight[12] . Ross’ mixed-deontological theory encompasses aspects of epistemology and intuitionism.

Criticisms
The main criticism of pure deontological ethics is the belief that a conflict in duties will never arise[13] . For example, if a wanted murderer asked you the location of his/her next victim, and that location was known to you, you would be obligated to tell the wanted murderer said location, or you would be performing the immoral act of lying. There are situations “where compliance with deontological norms will bring about disastrous consequences”[14] . Other common criticisms of deontological theory include the fact that it does not readily allow for grey areas regarding questions of morality, and that pure deontological theory leaves individuals uncertain of which duties qualify as those which we should all follow[15] .